//
// detail/is_executor.hpp
// ~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2022 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#ifndef ASIO_DETAIL_IS_EXECUTOR_HPP
#define ASIO_DETAIL_IS_EXECUTOR_HPP

#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)

#include "asio/detail/config.hpp"
#include "asio/detail/type_traits.hpp"

#include "asio/detail/push_options.hpp"

namespace asio {
    namespace detail {

        struct executor_memfns_base {
            void context();

            void on_work_started();

            void on_work_finished();

            void dispatch();

            void post();

            void defer();
        };

        template<typename T>
        struct executor_memfns_derived
                : T, executor_memfns_base {
        };

        template<typename T, T>
        struct executor_memfns_check {
        };

        template<typename>
        char (&context_memfn_helper(...))[2];

        template<typename T>
        char context_memfn_helper(
                executor_memfns_check<
                        void (executor_memfns_base::*)(),
                        &executor_memfns_derived<T>::context> *);

        template<typename>
        char (&on_work_started_memfn_helper(...))[2];

        template<typename T>
        char on_work_started_memfn_helper(
                executor_memfns_check<
                        void (executor_memfns_base::*)(),
                        &executor_memfns_derived<T>::on_work_started> *);

        template<typename>
        char (&on_work_finished_memfn_helper(...))[2];

        template<typename T>
        char on_work_finished_memfn_helper(
                executor_memfns_check<
                        void (executor_memfns_base::*)(),
                        &executor_memfns_derived<T>::on_work_finished> *);

        template<typename>
        char (&dispatch_memfn_helper(...))[2];

        template<typename T>
        char dispatch_memfn_helper(
                executor_memfns_check<
                        void (executor_memfns_base::*)(),
                        &executor_memfns_derived<T>::dispatch> *);

        template<typename>
        char (&post_memfn_helper(...))[2];

        template<typename T>
        char post_memfn_helper(
                executor_memfns_check<
                        void (executor_memfns_base::*)(),
                        &executor_memfns_derived<T>::post> *);

        template<typename>
        char (&defer_memfn_helper(...))[2];

        template<typename T>
        char defer_memfn_helper(
                executor_memfns_check<
                        void (executor_memfns_base::*)(),
                        &executor_memfns_derived<T>::defer> *);

        template<typename T>
        struct is_executor_class
                : integral_constant<bool,
                        sizeof(context_memfn_helper<T>(0)) != 1 &&
                        sizeof(on_work_started_memfn_helper<T>(0)) != 1 &&
                        sizeof(on_work_finished_memfn_helper<T>(0)) != 1 &&
                        sizeof(dispatch_memfn_helper<T>(0)) != 1 &&
                        sizeof(post_memfn_helper<T>(0)) != 1 &&
                        sizeof(defer_memfn_helper<T>(0)) != 1> {
        };

        template<typename T>
        struct is_executor
                : conditional<is_class<T>::value,
                        is_executor_class<T>,
                        false_type>::type {
        };

    } // namespace detail
} // namespace asio

#include "asio/detail/pop_options.hpp"

#endif // ASIO_DETAIL_IS_EXECUTOR_HPP
